1. Field of the Invention
The present invention relates to a starting clutch that is provided on the input side of a transmission mechanism of a vehicle transmission.
2. Description of the Prior Art
A starting clutch used for starting a vehicle is provided on the input side of a transmission mechanism. The starting clutch is disengaged while the engine is idling. When the vehicle starts running, for example, after a gear position for starting such as first speed gear has been set, the starting clutch is fully engaged after passing through a partially engaged state so as to transmit torque from the engine to the transmission mechanism.
Technology relating to a starting clutch is disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 10-78052. In the technology of the publication No. 10-78052, a simplification and a decrease in weight of the structure of the starting clutch are aimed.
A description will now be given of the structure of this starting clutch. A cylindrical sleeve is fixed at the outer periphery of an end portion on the drive plate side of an input shaft of the transmission mechanism. A drum is fixed in connection with the sleeve. A pressure plate and a plurality of ring-shaped plates are spline fitted to the inner periphery of the cylindrical portion of the drum.
A hub that faces the cylindrical portion of the drum is disposed on the input shaft via a bearing so as to be freely rotatable. The hub is linked to the drive plate via a cylindrical case and the drum is disposed inside this case. Between the hub and the cylindrical portion of the drum, a plurality of ring-shaped discs that are capable of movement in an axial direction are fitted via a spline to the outer periphery of the hub. These discs and the aforementioned plates are provided in alternation and when the starting clutch is engaged, the discs and plates are united by the pressing force so as to transmit the rotation.
The discs that are fitted to the hub on the driving side to which the driving force of the engine is transmitted via the drive plate have a comparatively thin plate thickness, while the plates that are fitted to the drum on the driven side have a comparatively thick plate thickness.
In many vehicles, in order to prevent shock when the starting clutch is engaged, it is normal for a torsional damper to be installed between the engine torque output portion and the drive side drum.
However, when a torsional damper is used, in the structure in the above described conventional technology, the drive side inertial mass of the starting clutch is small, and the concern exists that resonance from torsional vibration in the drive system will be generated while the engine is idling and the starting clutch is disengaged.
Namely, in the conventional technology, because a hub having a small diameter is on the drive side, while a drum having a large diameter is on the driven side, and because comparatively thin discs are provided for the hub, while comparatively thick plates are provided for the drum, the inertial mass on the drive side is small. As a result, there is a strong possibility of torsional vibration resonance being generated in the vicinity of the idling speed.
Therefore, the present invention has been conceived in order to solve the above problem in the conventional technology, and it is an object thereof to provide a starting clutch that prevents resonance from torsional vibration in the drive system being generated while the engine is idling.
The first aspect of the present invention is a starting clutch that is provided at an input side of a transmission mechanism of a vehicle transmission comprising: a drum for receiving rotation drive force from an engine via a torsional damper provided with a spring; a hub that is provided at an inner side of the drum and that is linked to an input shaft of the transmission mechanism; and drive side plates and driven side plates that mesh respectively with the drum and the hub and are stacked together in alternation, wherein a plate thickness of the drive side plates is made thicker than a plate thickness of the driven side plates.
By using this structure, the inertial mass on the drive side is increased and it is possible to prevent drive system torsional vibration resonance from being generated when the engine is idling.
Further, the increasing of the plate thickness is also connected to an increase in rigidity and an increase in the thermal capacity and also improves the judder resistance as well as the heat resistance and durability of the clutch.
In addition, by altering the plate thickness of the drive side plates, it is possible to adjust the drive side inertial mass in accordance with the engine side inertial mass.
In the second aspect of the present invention, the plate thickness of the drive side plates is set such that drive side inertial mass from a member that is linked to the drum, sandwiching the torsional damper spring and including the drive side plates, is 50% to 100% of engine side inertial mass from an engine side member.
By using this structure, it is possible to keep the weight increase caused by increasing the drive side inertial mass to the minimum.
In the third aspect of the present invention, a floating plate is provided between the driven side plates and a flange portion formed integrally with the hub.
By using this structure, it is possible to prevent the facing surface of the driven side plate from peeling or becoming abraded.
In the fourth aspect of the present invention, when no floating plate is provided, only the driven side plate closest to the flange portion is formed without a friction material being adhered to the surface of this driven side plate on the side that makes contact with the flange portion.
By using this structure, it is possible to prevent the facing surface of the driven side plate from peeling or becoming abraded even when no floating plate is provided.
In the fifth aspect of the present invention, the plate thickness of the drive side plates is made the same for each plate.
By using this structure, the heating value created by the friction is dispersed uniformly thereby increasing the heat resistance and durability.